I said that I had put in an NOS preamp tube the other day. I started playing it before that and noticed the reverb wasn't working. I switched 12AT7 tubes and played it again to see if the reverb came back. It did and after a couple of minutes the fuse blew. I got a new fuse and took out the NOS preamp tubes and played it again today. The fuse blew again. I notice that a Fender preamp tube I'm using really glows brighter than all the others. Could that be a sign that it's a bad tube? The amp is my vintage 1965 Super Reverb. It really sounds nice before it blows fuses. LOL!